5. CHANNEL
SELECTION
Select the desired output channel by setting the DIP switches according to the chart below.
6. ADJUSTMENT
a. After installation and completing all hardware connections power the unit and wait 20
minutes before making the following adjustments.
b. For testing purposes
no more than 15dB
from the
RF Output
should be going to a
TV or RF input monitor. Use an attenuator to reduce the signal level if testing with an
RF Input monitor. Individual CT-FSAM550 setup and level settings can be tested
from the
RF Output
port. However, system level testing should be done from the
combiner.
c. With a nominal 1 Vp-p video source connected, adjust the
VIDEO MODULATION
ADJUSTMENT
control. The video AGC circuit will automatically set the unit for
87.5% modulation over an input level of 0.5 to 1.5 volts peak-to-peak. If the video
input is greater than 1.5Vp-p, adjust the
VIDEO MODULATION LEVEL
for correct
percentage of modulation (87.5%). If test equipment is not available then adjust for
proper picture contrast when viewed on a TV monitor and compare with known Off-
Air broadcast picture quality.
d. With audio source connected, adjust
AUDIO MODULATION ADJUSTMENT
control
on the front panel for 25 KHz deviation using a precision demodulator and audio
meter. Instead of an audio modulation meter, use a TV set and adjust for equal
volume as compared to a known Off-Air broadcast. Monitor for a few minutes to
assure the maximum volume does not over modulate, which can cause picture
distortion.
e.
The aural carrier level should be adjusted to 15 dB below the level of the video carrier
by slowly rotation the
VIDEO AUDIO RATIO ADJUSTMENT
.
f. During field maintenance of the headend the CT-FSAM550’s
Output Test
port can
be used for taking unit measurements. However, note the output from the port is
padded down -30 dB and must be taken into consideration when adjusting levels.
7. TROUBLESHOOTING
a. Ensure you are using quality multiple shielded cables with quality radial or
compression F-connectors.
b. Ensure the F-connector’s center conductor is making solid contact with the CT-
FSAM550’s
Video Input, Audio Input, and RF Output
ports.
c. If the CT-FSAM550 is receiving power but no signal, check to be sure the video
and/or audio input cables are securely connected with their respective Video Output
and Audio Output ports on the video source and the Video Input and Audio Input
ports on the CT-FSAM550. Also ensure the cable is securely connected at the CT-
FSAM550’s
RF Output
port and the combiner’s input ports.
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